The International Hormone Society

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1 The International Hormone Society International office: Avenue Van Bever Brussels Belgium - European Union Fax: USA - address: 901 Dover Drive - Suite 210 Newport Beach, CA Fax: Phone: IHS.admin@yahoo.com References and additional information : APPENDIX 1. Thierry Hertoghe, MD, short curriculum vitae - President of the World Society of Anti-Aging Medicine (WOSAAM) - President of the International Hormone Society (IHS) - President of the European Academy of Quality of Life and Longevity medicine (Eaquall) - Scientific director of the Anti-aging Medicine World Congress, the European Congress of Anti-aging Medicine, and the Eurasian Congress of Anti-aging Medicine - Scientific director of the International English-speaking Anti-Aging Medicine Specialization of the WOSAAM - Scientific director of the International English-speaking Endocrinology and hormone therapy specialty of the IHS - Author of various books on the theme of hormone therapy translated into several languages (Spanish, Russian, Chinese, German, French, Danish, Dutch, etc.) including the Hormone Solution (Harmony Books-Randhom House New York), the Hormone Handbook for physicians and the Patient Hormone Handbook (International Medical Books Luxemburg) 3

2 APPENDIX 2: Narrower intraindividual variations in thyroid tests Narrower intraindividual variations in thyroid tests => Population-based reference range may not be adequate as each individual has a narrow reference range for health half of 1/3 in width compared to that of the population reference range 1. Andersen S, Pedersen KM, Bruun NH, Laurberg P. Narrow individual variations in serum T(4) and T(3) in normal subjects: a clue to the understanding of subclinical thyroid disease. J Clin Endocrinol Metab Mar;87(3): Department of Endocrinology, Aalborg Hospital, Aalborg, Denmark DK stiga@dadlnet.dk High individuality causes laboratory reference ranges to be insensitive to changes in test results that are significant for the individual. We undertook a longitudinal study of variation in thyroid function tests in 16 healthy men with monthly sampling for 12 months using standard procedures. We measured serum T(4), T(3), free T(4) index, and TSH. All individuals had different variations of thyroid function tests (P < for all variables) around individual mean values (set points) (P < for all variables). The width of the individual 95% confidence intervals were approximately half that of the group for all variables. Accordingly, the index of individuality was low: T(4) = 0.58; T(3) = 0.54; free T(4) index = 0.59; TSH = One test result described the individual set point with a precision of +/- 25% for T(4), T(3), free T(4) index, and +/- 50% for TSH. The differences required to be 95% confident of significant changes in repeated testing were (average, range): T(4) = 28, nmol/liter; T(3) = 0.55, nmol/liter; free T4 index = 33, nmol/liter; TSH = 0.75, mu/liter. Our data indicate that each individual had a unique thyroid function. The individual reference ranges for test results were narrow, compared with group reference ranges used to develop laboratory reference ranges. Accordingly, a test result within laboratory reference limits is not necessarily normal for an individual. Because serum TSH responds with logarithmically amplified variation to minor changes in serum T(4) and T(3), abnormal serum TSH may indicate that serum T(4) and T(3) are not normal for an individual. A condition with abnormal serum TSH but with serum T(4) and T(3) within laboratory reference ranges is labeled subclinical thyroid disease. Our data indicate that the distinction between subclinical and overt thyroid disease (abnormal serum TSH and abnormal T(4) and/or T(3)) is somewhat arbitrary. For the same degree of thyroid function abnormality, the diagnosis depends to a considerable extent on the position of the patient's normal set point for T(4) and T(3) within the laboratory reference range. 2. Andersen S, Bruun NH, Pedersen KM, Laurberg P. Biologic variation is important for interpretation of thyroid function tests. Thyroid Nov;13(11): Department of Endocrinology and Medicine, University Hospital Aalborg, Aalborg, Denmark. stiga@dadlnet.dk Large variations exist in thyrotropin (TSH) and thyroid hormones in serum. The components of variation include preanalytical, analytical, and biologic variation. This is divided into between- and within-individual variation. The latter consists of circadian and seasonal differences although there are indicators of a genetically determined starting point. The ratio of within- to between-individual variation describes the reliability of population-based reference ranges. This ratio is low for serum TSH, thyroxine (T(4)) and triiodothyronine (T(3)) indicating that laboratory reference ranges are relatively insensitive to aberrations from normality in the individual. Solutions are considered but reducing the analytical variation below the calculated analytical goals of 7%, 5% and 12% for serum T(3), T(4), and TSH does not improve diagnostic performance. Neither does determination of the individual set-point 4

3 and reference range. In practice this means that population-based reference ranges are necessary but that it is important to recognize their limitations for use in individuals. Serum TSH responds with amplification to minor alterations in T(4) and T(3). A consistently abnormal TSH probably indicates that T(4) and T(3) are not normal for the individual even when inside the laboratory reference range. This underlines the importance of TSH in diagnosis and monitoring of thyroid dysfunctions. Also, it implies that subclinical thyroid disease may be defined in purely biochemical terms. Under critical circumstances such as pregnancy where normal thyroid function is of importance for fetal brain development, subclinical thyroid disease should be treated. Even TSH within the reference range may be associated with slightly abnormal thyroid function of the individual. The clinical importance of such small abnormalities in thyroid function in small children and pregnant women for brain development remains to be elucidated. 3. Browning MC, Ford RP, Callaghan SJ, Fraser CG. Intra- and interindividual biological variation of five analytes used in assessing thyroid function: implications for necessary standards of performance and the interpretation of results. Clin Chem Jun;32(6): Intra- and interindividual components of biological variation have been determined for total thyroxin (TT4), free thyroxin (FT4), total triiodothyronine (TT3), free triiodothyronine (FT3), and thyrotropin (TSH). Calculated analytical goals (CV, %) for the precision required for optimal patient care are: TT4 less than or equal to 2.5, FT4 less than or equal to 4.7, TT3 less than or equal to 5.2, FT3 less than or equal to 3.9, and TSH less than or equal to 8.1. The marked degree of individuality demonstrated for all hormones indicates that, if conventional population-based reference ranges are used uncritically, major changes in hormone concentration may not be correctly identified for some patients because observed values continue to lie within the reference range. At analyte concentrations approximating the mean values found in this study, and for analytical performance meeting the appropriate analytical goal, the differences required for consecutive results to be significantly different (p less than or equal to 0.5) have been calculated as: TT4, 14.7 nmol/l; FT4, 5.7 pmol/l; TT3, 0.6 nmol/l; FT3, 1.3 pmol/l, and TSH, 0.7 milli-int. unit/l. 4. Nishi I, Ichihara K, Takeoka K, Miyai K, Amino N.[Intra-individual and seasonal variations of thyroid function tests in healthy subjects] [Article in Japanese] Rinsho Byori Feb;44(2): Central Laboratory for Clinical Investigation, Osaka University Hospital, Suita. We report intra-individual and seasonal variations of thyroid function tests in healthy subjects. Blood samples were obtained from thirteen healthy males and seven healthy females every two weeks over a period of one year, and totally 25 samplings of each were made. Serum thyrotropin (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) were measured after the completion of the sampling. The 25 samples from each subject were always assayed with the same assay run. Variations of FT4 and FT3 in each subject were narrow and approximately one-third of normal reference ranges. The magnitude of individual variation of TSH values was proportional to the average of TSH in each individual. Serum TSH and FT3 values during winter were significantly higher than those during summer, but such change was not observed on serum FT4. 5. Maes M, Mommen K, Hendrickx D, Peeters D, D'Hondt P, Ranjan R, De Meyer F, Scharpà S Components of biological variation, including seasonality, in blood concentrations of TSH, TT3, FT4, PRL, cortisol and testosterone in healthy volunteers. 5

4 Clin Endocrinol (Oxf) May;46(5): University Department of Psychiatry, Antwerp, Belgium. OBJECTIVE: There are few detailed studies of annual or seasonal variations in hormone concentrations in man. This study examines the components of biological variation, including seasonality, in plasma TSH, total T3 (TT3), free T4 (FT4), PRL, cortisol and testosterone in healthy volunteers. DESIGN: Monthly blood samplings for the assay of the above hormones were collected during one calendar year. SUBJECTS: Thirteen normal men and 13 normal women participated in the present study (mean age / years). MEASUREMENTS: Assays of TSH, TT3 and FT4 were carried out by means of immunoradiometric assays (IRMA), PRL by ELISA, cortisol by a fluorescence immunoassay, and testosterone with RIA. The time series were analysed by means of (bivariate or multivariate) spectral and cosinor analyses. RESULTS: Significant annual, four-monthly and biannual rhythms were detected in serum TSH; the lowest TSH values were observed in spring. A significant annual rhythm was detected in TT3, with lower values in spring and summer than in the other seasons. The peak-trough differences in the yearly variation expressed as a percentage of the mean were 29.1% and 8.2% for TSH and TT3, respectively. The yearly variation in plasma cortisol was significantly different between men and women: in men, 5.9% of the variation was explained by an annual rhythm, while in women 14.7% was explained by the fourth and seventh harmonical wave. The peak-trough differences in the yearly variation in plasma cortisol were 17.6% and 31.8% in men and women, respectively. There were no significant seasonal rhythms in PRL, FT4 or testosterone. The intraindividual/interindividual CV values were: TSH 29.3/48.4%, TT3 9.4/ 18.5%, FT4 7.1/9.1%, PRL 39.2/65.0%, cortisol 21.7/ 46.2%, and testosterone 12.6/40.8%. CONCLUSIONS: The degree of individuality measured in the plasma hormones is such that conventional population-based reference ranges may not correctly identify major alterations in these hormones in individual subjects. 6. Meier CA, Maisey MN, Lowry A, Müller J, Smith MA. Interindividual differences in the pituitary-thyroid axis influence the interpretation of thyroid function tests. Clin Endocrinol (Oxf) Jul;39(1): Department of Radiological Sciences, UMDS, Guy's Hospital, London, UK. OBJECTIVE: We investigated interindividual differences in the shape, slope and setpoint of the pituitary-thyroid axis (PTA) in normal persons. Based on these physiological data we propose a novel bivariate concept for the interpretation of thyroid function tests which is less biased by interindividual differences in the PTA than the currently used univariate approach. DESIGN: In two separate trials (A and B), healthy volunteers were given small, increasing doses of T3 ( micrograms/day orally) over 5 days. The regulation characteristics of the individual PTAs and the effects of age and gender were assessed by general linear regression models. In addition, serum samples were collected from normal persons to establish the proposed bivariate approach for the interpretation of thyroid function tests. SUBJECTS: The regulatory characteristics of the PTA were determined in a total of 21 normal volunteers (eight females, 13 males; age years). Single blood samples were collected from 257 normal volunteers. The participants had no history of pituitary or thyroid disease. MEASUREMENTS: Free and total thyroid hormone and TSH concentrations were determined in the serum. All samples from one person were analysed in the same assay in duplicate. RESULTS: A log-linear relationship between T3 and TSH was found to describe best the individual PTA (multiple r = 0.96). However, significant differences in the setpoint (P < 0.001) and to a lesser degree in the slope (P < or = 0.05) of the PTA were detected; this variability was not dependent on age or gender. Since 6

5 these findings invalidate the assumptions on which the current univariate interpretation of thyroid function tests is based, we propose a novel model for the evaluation of thyroid function tests derived from the experimentally determined shape and average slope of the PTA. CONCLUSIONS: The presence of significant age and gender-independent interindividual variations in the setpoint of the pituitary-thyroid axis raises conceptual problems with the current approach for interpreting thyroid function tests. An easy to use graphical bivariate representation of the normal ranges for thyroid function tests is presented and exemplified by the thyroid hormone and TSH measurements in a large reference population. This concept should improve the diagnostic accuracy in the borderline-normal, and particularly subclinical hypothyroid region of these hormone measurements. 7. Harrop JS, Ashwell K, Hopton MR. Circannual and within-individual variation of thyroid function tests in normal subjects. Ann Clin Biochem Jul;22 ( Pt 4): Blood was taken from normal subjects at monthly intervals over a period of one year for subsequent determination of serum thyroid hormone concentrations. Thyroid-stimulating hormone (TSH) responses to TSH-releasing hormone were performed at 3-monthly intervals. This study provided data on within-individual variation and on seasonally-related changes of these thyroid function tests. The results showed that, within an individual, thyroid hormone concentrations are maintained within narrow limits. For both thyroxine and triiodothyronine the component contribution of within-individual variation to the population-based variation (the latter also termed the 'reference interval', or colloquially the 'normal range') was small. This high degree of individuality implies that rigorous comparison of thyroid hormone results against a population-based 'normal range' can be potentially misleading. Despite the limited within-individual variation, seasonally-related changes in thyroid hormone concentrations were apparent, with higher thyroxine and triiodothyronine values seen in winter months. A tendency to a greater TSH response to TSH-releasing hormone was also noted at this time. Conceivably these changes could reflect a centrally-mediated response of the hypothalamic-pituitary-thyroid axis to environmental temperature. 8. Biersack HJ, Hartmann F, RÃ del R, Reinhardt M. Long term changes in serum T4, T3, and TSH in benign thyroid disease: proof of a narrow individual variation. Nuklearmedizin Oct;43(5):158-60; quiz Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany. Aim: The diagnosis of abnormalities of thyroid function is generally based on the measurement of thyroid hormones and TSH in blood. The recommended reference ranges for serum T4 and T3 as well as TSH are quite wide as the result of large differences in thyroid function tests in healthy persons. It has been proven that the individual variation within an individual is small, compared with the variation between individuals. We investigated long term variations of these parameters in patients with and without benign thyroid diseases. Methods: We performed long term follow-up serum determinations of T3, T4, and TSH in a total of 150 patients for a time period of 3 to 13 years. The majority of patients had been put on L-thyroxine. Values of total T3, total T4, free T4 were measured with an almost unmodified test (RIA) over the years. Results: The lowest relative coefficient of variation (<10%) was observed in the group of patients who had been treated with L-thyroxine only. Even for TSH, relatively low cofficients of variation were observed in this group. In the group of patients who had not received any medication, T3 and T4 showed also a variation of 10%. FT4 and TSH revealed a wider range of variation. Even after radioiodine therapy, T3 and T4 showed only a quite small variation, while TSH demonstrated a wide range with a 7

6 variation of >30%. Conclusion: Our data demonstrate that there are only narrow variations of serum T4 and T3 within individuals with and without thyroid disorders. 9. Nagayama I, Yamamoto K, Saito K, Kuzuya T, Saito T. Subject-based reference values in thyroid function tests. Endocr J Oct;40(5): Division of Endocrinology and Metabolism, Jichi Medical School, Tochigi, Japan. To evaluate the diagnostic value of subject-based reference values in thyroid function tests, we compared intra-individual and inter-individual variation. Five specimens were collected over a period of 2 weeks from each of 47 normal subjects, 29 women and 18 men, aged yrs. T4, FT4, T3, and FT3 were assayed by RIA, and TSH by a sensitive immunoradiometric assay. One-way ANOVA for each test was statistically significant for a main subject effect, indicating that the subjects differed in their personal mean values for the thyroid function tests (T4, P < 0.01; FT4, P < 0.05; T3, P < 0.01; FT3, P < 0.05; TSH, P < 0.01). The ratio value (intra- over inter-individual variation) was T4, 0.41; FT4, 0.60; T3, 0.53; FT3, 0.63; TSH The data indicate that conventional reference values are insensitive when compared to subject-based reference intervals in assessing the thyroid status of a given subject. Reactivity of the thyroid to the stimulation of endogenous TSH was assessed by the ratio delta FT 3/delta TSH in TRH stimulation tests. A positive correlation between basal FT3 and delta FT3/delta TSH (r = 0.566, P < 0.05) indicates that the thyroid with higher reactivity to TSH secretes more daily thyroid hormone. Negative correlation between basal TSH and delta FT3/delta TSH (r = , P < 0.05) means that a subject with lower reactivity of the thyroid needs a higher basal TSH level to compensate. The thyroid reactivity to TSH may be an important determinant for the individuality of the pituitary-thyroid axis. 10. Browning MC, Bennet WM, Kirkaldy AJ, Jung RT. Intra-individual variation of thyroxin, triiodothyronine, and thyrotropin in treated hypothyroid patients: implications for monitoring replacement therapy. Clin Chem Apr;34(4): Department of Biomedical Medicine, Ninewells Hospital and Medical School, Dundee, Scotland. We measured total thyroxin (TT4), free thyroxin (FT4), total triiodothyronine (TT3), free triiodothyronine (FT3), and thyrotropin (TSH) in serum sampled before and 1, 2, 4, 6, and 8 h after administration of prescribed doses of thyroxin to 12 patients with proven primary hypothyroidism. At 2, 4, and 6 h post-dose, the mean values for TT4 and FT4 and also that at 8 h for FT4 significantly (P less than 0.05) exceeded the corresponding pre-dose values. No significant changes were found for TT3, FT3, or TSH. The mean intra-individual CVs over the study period were TT4 4.9%, FT4 5.7%, TT3 8.7%, FT3 8.7%, and TSH 20.2%. Individual subjects showed small but predictable changes in TT4 and FT4. Changes in TT3 and FT3 were greater but random. Fluctuations in TSH were greatest, but in all subjects with detectable concentrations the variations were of similar magnitude. We conclude that strict adherence to timing of specimen collection in relation to dosage is probably unnecessary. Different reference ranges for different populations may be needed 11. Hubl W, Schmieder J, Gladrow E, Demant T. Reference intervals for thyroid hormones on the architect analyser. Clin Chem Lab Med Feb;40(2): Institut fã¼r Klinische Chemie und Laboratoriumsmedizin, Krankenhaus Dresden-Friedrichstadt, Dresden, Germany. hubl-wa@khdf.de The objective of this study was to establish reference intervals for thyroid 8

7 stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total thyronine (TT4) and total triiodothyronine (TT3) on the Architect i2000 analyser (Abbott). Serum samples were obtained from apparently healthy adults (n=217, age years) excluding individuals taking oral contraceptives or under hormone replacement therapy. The second group were ambulatory euthyroid patients (n=323) excluding those with a history of thyroid disorders. We also investigated thyroid hormones in sera from euthyroid hospitalised patients (n=490) excluding those with severe non-thyroidal illness. The reference intervals for the healthy adults were for TSH miu/l, for FT pmol/l, for FT pmol/l, for TT nmol/l and for TT nmol/l. TSH and TT3 concentrations were similar in males and females. However, FT4, FT3 and TT4 levels exhibited significant differences between females and males. No significant differences were observed between the concentrations of TSH, FT3, TT3, FT4 and TT4 in healthy subjects and in euthyroid ambulatory patients aged years. TSH levels in healthy subjects were the same in younger and older individuals. In contrast, in outpatients and in hospitalised patients TSH concentrations were significantly lower (20%) in subjects older than 50 years compared to those younger than 50 years. For FT3 and TT3 we consistently observed in all three study groups 6-7% and 8-12% higher concentrations in the younger (< 50 years) compared to the older (> 50 years) subjects. For FT4 and TT4 no consistent pattern of correlation with age was detectable when the three study groups were analysed independently. The reference intervals for thyroid hormones determined in this study differ considerably from values found in other European and non-european countries. This underlines the need for population-specific reference ranges. 12. Dhatt GS, Griffin G, Agarwal MM. Thyroid hormone reference intervals in an ambulatory Arab population on the Abbott Architect i2000 immunoassay analyzer. Clin Chim Acta Feb;364(1-2): Epub 2005 Aug 10. Department of Pathology, Tawam Hospital, PO Box 15258, Al Ain, Abu Dhabi, United Arab Emirates. gurdeep1@emirates.net.ae BACKGROUND: Considerable differences in reference intervals for FT4 and TSH have been reported between countries. Method related differences in the distribution of free thyroxine (FT4) have also been reported. The aim of this study was to establish reference intervals for thyrotrophin (TSH) and FT4 in an ambulatory adult (16-75 y) Arab population attending a general practice clinic using the Abbott Architect i2000 immunoassay analyzer. METHODS: TSH and FT4 results from 959 consecutive ambulatory Arab subjects were available. After excluding data sets from pregnant women, patients with known and newly diagnosed thyroid disease, individuals taking medication that may affect TSH and FT4 and individuals with acute illness, 742 data sets were available for analysis. A 2-way between-groups ANOVA was conducted to explore the impact of age and gender on TSH and FT4. RESULTS: TSH showed a non-gaussian distribution, FT4 showed a near normal distribution. There was no significant main effect on FT4 and TSH for age and gender. The interaction effect of age and gender also did not reach significance. The 95% reference intervals were: TSH mu/l and FT pmol/l. The reference intervals for TSH and FT4 determined in this study differed from those reported from other countries using the same analytical platform and from the 99% reference intervals, provided by the manufacturer. CONCLUSIONS: These differences in reference intervals in different populations may affect patient management. The data reported reemphasize that each laboratory should determine population and method-specific reference intervals. 9

8 Broadening of the thyroid reference ranges due to inclusion of elderly persons 13. Gonzàlez-Sagrado M, MartÃn-Gil FJ. Population-specific reference values for thyroid hormones on the Abbott ARCHITECT i2000 analyzer. Clin Chem Lab Med May;42(5): Unidad de Apoyo a la Investigación, Hospital Universitario "Del RÃo Hortega" Valladolid, Spain. gonzalez-sagrado@arrakis.es Reliable reference ranges are important in the interpretation of laboratory data, and it is incumbent on each laboratory to verify that the ranges they use are appropriate for the patient population they serve. The objective of this study was to determine population-specific reference ranges for thyroid stimulating hormone (TSH), free thyroxine (ft4), free triiodothyronine (ft3) and total triiodothyronine (TT3) on the Abbott ARCHITECT analyzer. For this study, we used human serum samples collected from a population in Castilla y León, Spain. Serum samples were collected from 304 individuals (male, n = 151; female, n = 153; age years) representing outpatients (n=100), hospitalized patients (n = 104) and apparently healthy subjects (n = 100). Individuals taking any medications, with a history of thyroid disorder, or severe non-thyroidal illness were excluded from the study. For healthy subjects, the following reference intervals were determined: TSH, mlu/l; ft4, ng/dl ( pmol/l); ft3, pg/ml ( pmol/l); and TT3, ng/ml ( nmol/l). In this group, TSH and ft4 showed significant differences between men and women, but ft3 and TT3 did not. Conversely, ft3 and TT3 showed significant age-related differences, but TSH and ft4 did not. Within the outpatient group, no significant differences were seen between men and women for any of the hormones, but age-related differences were significant for ft3 and TT3. Within the hospitalized patient group, significant differences between men and women were found for TSH only, and age-related differences were significant for TSH, ft3 and TT3. Our findings are basically in accordance with previously published results for ft3, TT3 and TSH, but for ft4 our results differ from other data in the literature. This highlights the need for laboratories to confirm that the reference ranges they use are appropriate for the population they serve. 14. Davey R. Thyroxine, thyrotropin, and age in a euthyroid hospital patient population. Clin Chem Nov;43(11): Western Hospital, Footscray, Australia. Richard.Davey@whcn.org.au The diagnosis of thyroid disease now often can be achieved reliably by measuring thyrotropin (TSH) alone. Thyroxine (T4), triiodothyronine, and other analytes are only needed if TSH and the accompanying clinical condition are discordant. We describe here work that confirms the age independence of TSH in both inpatient and outpatient euthyroid hospital populations between ages 20 and at least 80 years, and demonstrates that although free T4 does vary with age, the range of variation remains within the T4 reference interval. On this basis, TSH-based thyroid diagnostic algorithms can be used reliably in adults without reference to age-related reference intervals. Broadening of the thyroid reference ranges due to inclusion of sick person 15. Midgley JE, Gruner KR. Effects of age and health on the euthyroid reference ranges for serum free thyroxine and free triiodothyronine. Nuklearmedizin Apr;24(2): Age-related trends in serum free thyroxine (FT4) and free triiodothyronine (FT3) concentrations were measured in 7248 euthyroid subjects (age-range 3 months to 106 years) were patients referred to hospitals for investigation of 10

9 suspected thyroid dysfunction, but who were diagnosed euthyroid were healthy blood donors (age-range years) with no indication of thyroid dysfunction. FT4 concentrations were little affected by the age, the sex or the state of health of the subjects in either group. Serum FT3 concentrations were significantly affected by both age and health factors. The upper limit of the euthyroid reference range for young subjects up to 15 years was about 20% higher (10.4 pmol/l) than for adult subjects older than 25 years (8.8 pmol/l). The change in the upper limits typical of young subjects to that typical of adults occurred steadily over the decade years. After this age, little further change occurred, especially in healthy subjects. Additionally, the lower limit of the euthyroid range for FT3 was extended by the inclusion in the reference group of patients referred to hospitals. Compared with the lower limit of the FT3 range for healthy subjects (5 pmol/l), the corresponding limit for referred subjects (young or adult) was pmol/l. Broadening of the FT3 reference range was probably brought about by a significant number of patients in the hospital-referred group with the "low-t3 syndrome" of mild non-thyroidal illness. Accordingly, FT3 was inferior to FT4 in the discrimination of hypothyroidism, as FT4 was unaffected by this phenomenon.(abstract TRUNCATED AT 250 WORDS) Misinterpretation of an abnormal laboratory value as an aging change can lead to underdiagnosis and undertreatment in some instances (such as anemia). 16. Melillo KD. Interpretation of laboratory values in older adults. Nurse Pract Jul;18(7): Graduate Nursing Program, College of Health Professions, University of Massachusetts, Lowell. This article describes age-related physiologic changes in the older adult and the effect of these changes, if any, on commonly ordered laboratory tests. As reported in selected research studies and literature reviews, some laboratory parameters change minimally or not at all with age, still remaining within recommended reference ranges, while others are altered with age. Misinterpretation of an abnormal laboratory value as an aging change can lead to underdiagnosis and undertreatment in some instances (such as anemia). Failure to appreciate age-related changes can lead to overdiagnosis and overtreatment in others (such as hyperglycemia). The results from ongoing national studies are needed to establish uniform older adult reference intervals. 11

10 APPENDIX 3: IHS consensus 9 with references The International Hormone Society Consensus # 9 on The treatment of clinically hypothyroid, but biochemically euthyroid patients April 12, 2007 After an extensive literature review and discussions with physicians from all over the world who are well versed in treating patients with endocrine abnormalities, we, the Consensus Group of Experts of the International Hormone Society (IHS), think there is enough clinical and theoretical evidence to expand the application of thyroid treatment beyond the current conventional parameters. Is the diagnosis of hypothyroidism based on biochemical evaluation or clinical evidence? There is a controversy between groups of physicians. One group essentially diagnoses hypothyroidism solely with laboratory tests, while the other relies more on clinical factors. Solid scientific evidence does not support the idea that the diagnosis of hypothyroidism can or should only be based on laboratory tests. This would imply that hypothyroidism only exists in patients with a serum TSH beyond the actual upper reference range, and serum thyroxine (T4) and triiodothyronine (T3) levels below the lower reference range, and neglects the clinical signs and symptoms. The IHS's position is intermediate. The decision to initiate (thyroid) therapy should be based on both clinical and laboratory findings, and not solely on the results of a single test, exactly as expressed in the medical journals JAMA and Thyroid presenting the American Thyroid Association's guidelines for use of laboratory tests in thyroid disorders 1. The diagnosis of hypothyroidism is further substantiated when treatment results in the relief of clinical signs and symptoms and the laboratory tests are improved. Clinical information is essential in diagnosing a hormone deficiency. The clinical data needed to make a diagnosis of hypothyroidism include the physical and emotional complaints of patients, physical signs, personal and familial medical histories suggestive of a thyroid deficiency and the existence of a thyroid gland abnormality (nodule or goiter) and/or autoimmune thyroiditis. The following evidence supports the existence of patients who are clinically hypothyroid, but mistakenly considered biochemically euthyroid, and who may benefit from thyroid treatment: 1) The normal reference ranges for thyroid tests are too broad and ignore specific individual reference ranges. Excessively broad reference ranges: Large reference intervals may include serum levels of T3, T4 and TSH that are compatible with thyroid dysfunction, in particular, with various degrees of mild thyroid failure. The experts on the consensus panel did not find any studies proving that the normal thyroid test reference ranges discriminate adequately 12

11 between hypo-, eu- and hyperthyroidism. On the contrary, we found studies whose data questioned the usefulness of these reference ranges, in particular, for serum TSH, T3 and T4. The data from these studies support the use of narrower ranges for these serum tests. The broader reference ranges include levels that may be consistent with thyroid dysfunction, especially in its milder forms. This is not surprising, as the reference ranges of a test are not values indicative of health, but merely values found in 95% of a population, generally the population of patients going to the laboratory. Levels compatible with both health and (thyroid) disease may be included. The TSH reference range: The difference between the upper and lower ends of the reference range is more than 20-fold ( miu per liter). o o In several studies, a serum TSH above 1.5 or 2 miu per liter has been linked with increased hypothyroid-associated lipid and inflammatory pathologies (such as higher serum levels of homocysteine, cholesterol and highly sensitive CRP). These higher TSH levels have also been linked with coronary and vascular abnormalities (such as higher coronary artery diseases scores, increased risk of multi-vessel disease, increased arterial stiffness), lower birth weight, premature birth of children from mothers with TSH above 2, and an increased risk of progression from mild to overt hypothyroidism. Depending on the study, at TSH levels above 0.4 or 0.9 miu per liter there is an increased risk of thyroid malignancy in patients with morphological abnormalities of the thyroid. The increased risk may be reversed by treatment with thyroid medication. Other disorders have been observed in patients with a serum TSH within the reference range but above the 25 th percentile such as a higher risk of severe depression, a poorer response to antidepressants, an increased incidence of somatic disease, a higher body mass index, an increased waist circumference, higher systolic and diastolic blood pressures, and higher serum glucose and triglycerides. Medicating these patients who are apparently in mild thyroid failure and have a high risk of becoming overtly hypothyroid may prevent the important sequellae associated with the progression of hypothyroidism. Other data support the need for improved serum TSH reference ranges. If the serum TSH reference range is based upon a cohort of truly normal individuals, for example, with no personal or family history of thyroid dysfunction, no visible or palpable goiter, no medication use, no thyroid peroxidase antibodies and with fasting blood samples taken in the morning (6 10 AM) then the TSH reference range would be miu per liter. The data support the acceptance of a value below 3 as an upper limit for the TSH reference range. When data for subjects with positive thyroid peroxidase antibodies or a family history of autoimmune thyroid disease are excluded, the normal reference interval becomes much tighter, i.e miu per liter. o Moreover, the results of several investigations indicate a mean serum TSH of 1.5 miu per liter for an iodine-sufficient population, demonstrating that the reference range of miu per liter is far too broad. o o Ethnic differences should also be taken into account: A study has shown the mean TSH level in African-Americans to be 1.18 mu/liter, in contrast to a mean of 1.40 mu/liter in Caucasians, due to the greater frequency of autoimmune thyroid disease in whites. This may have skewed the upper end of the TSH curve (NHANES data). For African-Americans, the TSH reference range is possibly lower than in whites. The American Association of Clinical Endocrinologists in 2002 therefore narrowed the serum TSH reference range to miu/l, lowering the upper reference end to 3. The National Academy of Clinical Biochemistry reduced the upper end of the reference range from 5.5 to 4.1 miu per liter in The latter group also stated 13

12 that more than 95% of healthy, euthyroid subjects have a serum TSH between miu per liter" and that patients with a serum TSH above 2.5 miu per liter, when confirmed by repeat TSH measurement made after three to four weeks, may be in the early stages of thyroid failure, especially if thyroid peroxidase antibodies are detected. In 2003, the consensus panel (Endocrine Society, American Association of Clinical Endocrinologists, and American Thyroid Association) recommended a target TSH range of 1.0 to 1.5 miu per liter in patients already receiving thyroxine therapy. o Erroneously low TSH: Some patients may suffer from centralized hypothyroidism and will have a low TSH even with a low T4 and a low T3. TSH is currently the primary thyroid screening test recommended. In this population of patients, a hypothyroid disorder will be missed if the low TSH is not followed up by testing free T3 and free T4. Serum free T3 and T4 reference ranges: The difference between the upper and lower reference ends is more than two-fold ( ng per liter for free T3 and ng per deciliter for free T4). Although the size of the reference range of free, unbound thyroid hormones is less impressive than that of serum TSH, a patient whose thyroid hormones are borderline high (while still within the normal reference range) may have twice the amount of thyroid hormones in his/her blood than a patient who is borderline low (but also in the reference range of euthyroid patients). If one of these patients is clinically well, then the other probably has a thyroid dysfunction. Patients with a serum T3 in the lower third of the reference range have been documented to undergo more inflammatory processes, to have an increased risk of breast cancer and increased severity of coronary heart disease. Cardiac function has been observed to be decreased in patients with serum T3 in the lower quintile (20%) of the reference range. Studies can be found where lower serum free or total T3 levels within the reference range are correlated with increased severity of illness and/or worse prognosis of a disease, including an increased mortality rate. This is particularly true in cases of myocardial infarction, chronic heart failure and stroke. For serum T4 values within the lower half of the normal reference range in children, there are reports that maximal intellectual development has been impaired, while in the same lower half of the serum T4 range, the rate of depression in patients with Alzheimer s disease appears to be significantly higher. Moreover, a serum T4 in the lower third of the reference range has been associated with increased insulin resistance, premature atherosclerosis (with significantly higher levels of CRP), increased memory loss, and increased mortality. There is enough data to support the need for a profound revision of thyroid hormone reference ranges, where narrower reference ranges with higher lower ends would provide more useful, truly healthy, reference ranges. Need for narrower reference ranges for thyroid tests: In light of the above data and considerations, the IHS consensus panel of experts stresses the importance of undertaking studies to establish more accurate and narrower reference ranges that reflect true euthyroidism. Narrower reference ranges allow more patients with mild thyroid failure or excess to be detected and treated. Mild thyroid failure is reflected by borderline low serum T3 and T4 and/or borderline high serum TSH. The panel is aware of at least one study in which the treatment of clinically hypothyroid, but biochemically euthyroid, patients was done using thyroxine with no beneficial result. Possibly, the dose or the type of thyroid treatment, namely thyroxine alone, was insufficient to obtain beneficial clinical results. A higher dose or a combined thyroxine-triiodothyronine medication might have been more appropriate. In one study of patients with coronary heart disease, for example, the progression of coronary atherosclerosis over one year was apparent in all patients taking 100 micrograms or less of thyroxine per day, while only one sixth of patients taking 150 micrograms or more had disease progression. Earlier studies have shown significantly better efficacy of combined thyroxintriiodothyronine medications, compared to thyroxine alone. Improvement was found in 14

13 such divergent parameters as serum cholesterol, mental and physical symptoms, and, in animals, goiter formation and intracellular triiodothyronine (T3) euthyroidism, to name a few of the possible increased benefits. Specific individual reference ranges: The optimal reference ranges for an individual can be different from the population reference ranges used by laboratories. Individual reference ranges are usually narrower (for example, 0.5 to 1.5 miu per liter of serum TSH, rather than ). Moreover, specific cut-off points between eu- and hypothyroidism may differ from one individual to another. One person may be euthyroid at a serum TSH of 0.5 and hypothyroid at 0.6, while another may be euthyroid at a TSH of 2 and hypothyroid at 2.1. Because of such inter-subject variations, when the results of thyroid tests don t match the clinical picture of thyroid dysfunction, the clinical impression of the experienced physician who has examined the patient should prevail and, if the patient is clinically hypothyroid, a therapeutic trial of thyroid hormones administered, starting at low doses. Tertiles, quartiles or quintiles of insufficiency may have to be considered to diagnosis hypothyroidism, rather than values below or above the reference range. Serum levels of thyroid hormones in the lower tertile, quartile or quintile, and serum levels of TSH in the upper half of the reference range, have been associated with increased disease and mortality rates, as mentioned above. 2) Excessive fluctuations of serum levels of T3, T4 and TSH: Differences up to three-fold in serum TSH and serum T4 have been found within the same individual during a single day. Such dramatic variations put the reliability of thyroid tests in question. At the time of the blood draw a person may be at his/her lowest TSH level, which is well under the upper reference range and looks reassuringly normal, while at other times s/he may be clearly above the upper reference range with a value consistent with subclinical or even overt hypothyroidism. 3) Thyroid dysfunction at the cellular level, undetectable by classical laboratory tests. A lack of thyroid activity may also be caused by a decline in the number, availability or affinity of thyroid nuclear cell receptors, in particular of T3. It is known from animal experiments that thyroid (T3) nuclear cell receptors decrease with age. This has also been observed in some human hormone deficiencies such as Addison s disease. A decline in cell receptors cannot be confirmed by classical thyroid tests, as tests for T3 nuclear cell receptors are not currently available in conventional laboratories. The only way to detect insufficient thyroid cell receptors is to evaluate the psychological and somatic effects of thyroid hormones on the body. This must be done through physical examination and interview, checking for hypothyroid signs and symptoms. Useful information might be deduced by testing the peripheral effects of thyroid hormones on serum parameters that increase in proportion to thyroid activity, such as serum SHBG (sex hormone binding globulin), alcalin phosphatase or osteocalcin, and/or that decrease with increasing thyroid function, such as serum total cholesterol. Alternatively, we could test for direct metabolites of T3, namely the T2 s (diiodothyronines), but these tests are not yet available. Furthermore, even if thyroid hormone serum levels and receptors are optimal, vitamins, trace elements, minerals or amino acids necessary for enzyme production or function could be deficient, thereby reducing the efficacy of metabolic reactions under control of thyroid hormones. Thyroid treatment of clinically hypothyroid, though biochemical euthyroid, patients: If a patient is clinically hypothyroid, presenting with several signs and symptoms of hypothyroidism, but is considered biochemically euthyroid, with low normal laboratory levels of serum T3 and/or T4, and/or high normal serum TSH according to the actual reference range, a trial of thyroid therapy may be started to see if the patient s signs and symptoms regress under therapy. Thyroid hormone levels may be considered low normal when in the lower third or half of 15

14 the reference range, while the serum TSH may be considered high normal when in the upper third or half of the actual TSH reference range ( mu per liter). In these zones, the patient may be hypothyroid, as demonstrated by several studies in which hypothyroidism is reflected by upcoming disorders such as lipid, vascular, cardiac, insulin and mental disturbances, and cancer and mortality risks, and sharp increases in risk of progression to overt hypothyroidism, as discussed above. These pathologies suggest mild thyroid failure that may regress under therapy. We recommend that physicians be careful to exclude, before thyroid intervention, other pathologies that may explain the symptoms. A trial of thyroid hormones should be started at low doses that are progressively increased, and progress should be carefully evaluated, taking care that the patient is not overdosed. Is there any danger in treating thyroid dysfunction? The most common adverse effect is iatrogenic hyperthyroidism. This is caused either by overdose or intolerance. Intolerance with peaks of T3-hyperthyroidism can be caused by excess conversion of thyroxine (T4) into triiodothyronine (T3), thus accelerating thyroid activity, and is more likely to occur with other hormone deficiencies, such as an adrenal insufficiency (cortisol), a lack of estrogens, and other hormone inadequacies that stimulate the conversion of T4 to T3. Safety can be increased by starting at low doses. Follow-up on thyroid treatment of clinically hypothyroid, though biochemical euthyroid, patients: Under treatment, most initially clinically hypothyroid (though mistakenly considered biochemically euthyroid) patients, should have normal lab values (with levels of T3, T4 and TSH inside the reference range when the tests are done more than 9 hours after taking thyroid medication). They should become clinically euthyroid. However, peak serum levels of T4 and T3 may be found that are not representative of the patient s real thyroid activity during the first 9 hours after intake of thyroid medication, and some studies suggest that between 36 and 47 % of patients clinically euthyroid under thyroid therapy have an undetectable serum TSH. Conclusion: Clinically hypothyroid, though biochemically euthyroid, patients may have a mild degree of thyroid failure. Such patients may benefit from a trial with thyroid hormones starting at low doses that are progressively increased. Before commencing the trial, other pathologies that may be causing the clinical signs and symptoms should be excluded. Careful monitoring is recommended. 1. JAMA 1993, 269:2736, Thyroid, 1993; 3 (4): References of Consensus 9 on the Treatment of Clinically Hypothyroid, but Biochemically Euthyroid Patients I. Diagnosis of hypothyroidism Publications that stress the importance of both clinical and biochemical assessments in the evaluation of thyroid function 1. (No author listed). Optimal use of blood tests for assessment of thyroid function. JAMA 1993;269:2736; Thyroid. 1993;3(4): Larsen PR, Davies TF, Hay ID. Symptoms of hypothyroidism. In Williams Textbook of endocrinology. 9th ed., WB Saunders: p. 461, table (data from Ateans JH. The thyroid and its diseases. 2nd ed. JB Lippincott, Philadelphia 1948: 233) 3. Wiersinga WM. Hypothyroidism and myxedema coma. 105: 1491 In Endocrinology, 4th ed., Degroot LJ, Jameson JL. Ed., 2: 16

15 4. Zulewski H, Muller B, Exer P, Miserez AR, Staub JJ. Estimation of tissue hypothyroidism by a new clinical score: evaluation of patients with various grades of hypothyroidism and controls. J Clin Endocrinol Metab. 1997;82:771 6 II. The reference ranges of normality for the thyroid tests are too wide and do not take into account specific individual reference ranges A. Studies that show association of disease (markers) with serum T3 levels within the reference range These associations are evidence suggesting that not all T3 levels within the reference ranges are healthy; some may be indicative of mild thyroid failure, and thus require correction with thyroid replacement Serum free T3 (ft3) pmol/l pg/ml Highest tertile 3.1 pg/ml Middle tertile 2.8 to 3.09 Lowest tertile < 2.79 Auer J, et al.. Clin Cardiol Dec;26(12): Studies with data that indicate that 1) The healthiest serum T3 levels may be found in the upper tertile (33%) of the reference range Study with suggestion that a healthy serum freet3 should be in the upper two tertiles (upper 67%) of the reference range, and preferably in the upper tertile, in hemodialysis patients, otherwise, in particular in case of serum T3 in the lower tertile, there may be a higher risk of abnormal inflammatory markers (such as increases in serum interleukin-6 and C-reactive protein) markers of endothelial activation (intercellular adhesion molecule-1 [ICAM-1] and vascular cellular adhesion molecule-1 [VCAM-1]) (strong and inverse associations between free T3 and IL-6, C-reactive protein, ICAM-1, and VCAM-1) 5. Zoccali C, Tripepi G, Cutrupi S, Pizzini P, Mallamaci F. Low triiodothyronine: a new facet of inflammation in end-stage renal disease. J Am Soc Nephrol Sep;16(9): CNR-IBIM, Clinical Epidemiology and Pathosphysiology of Renal Diseases and Hypertension, Ospedali Riuniti, Calabria, Italy. carmine.zoccali@tin.it Study with suggestion that a safe serum free T3 in elderly patients with heart failure should be above 80 ng/dl (upper limit of the lower tertile of the reference range), and preferably in the upper tertile (33%), otherwise the risk of adverse cardiovascular event may be significantly higher 6. Rays J, Wajngarten M, Gebara OC, Nussbacher A, Telles RM, Pierri H, Rosano G, Serro-Azul JB. Long-term prognostic value of triiodothyronine concentration in elderly patients with heart failure. Am J Geriatr Cardiol Sep-Oct;12(5): Division of Geriatric Cardiology, Heart Institute (InCor), University of Sao Paulo Medical School, Sao Paolo, Brazil. Study with suggestion that a healthy serum free T3 should be above the lower tertile (33%), and preferably in the upper tertile (33%) of the reference range in postmenopausal women, otherwise the risk of breast cancer may be highly increased 7. Strain JJ, Bokje E, van't Veer P, Coulter J, Stewart C, Logan H, Odling-Smee W, Spence RA, Steele K. Thyroid hormones and selenium status in breast cancer. Nutr Cancer. 1997;27(1): Human Nutrition Research Group, University of Ulster, Coleraine, Northern Ireland. Study with suggestion that a healthy serum free T3 should be equal to or above 2.8 pg/ml (just above the lower tertile in patients who undergo coronary angiography, otherwise the risk is higher for having an increased severity of coronary artery atherosclerosis 8. Auer J, Berent R, Weber T, Lassnig E, Eber B. Thyroid function is associated with presence and severity of coronary atherosclerosis. Clin Cardiol Dec;26(12): Second Medical 17